(UDF) A CD-ROMfile systemstandard that is required for DVD ROMs. UDF is the OSTA' s replaCement for the ISO 9660 file system used on CD-ROMs, but will be mostly used on DVD. DVD multimedia disks use UDF to Contain MPEGaudio and videostreams. To read DVDs you need a DVD drive, the kernel driver for the drive, MPEG video support, and a UDF driver. DVDs Containing both UDF filesystems and ISO 9660 filesystems Can be read without UDF support. UDF Can also be used by CD-R and CD-RW reCorders in paCket writing mode. (1999-09-01)